An apparatus arranged to emit a laser beam onto a workpiece to practice various laser machining, e.g., cutting and welding of the workpiece, is conventionally known. If the laser beam to be emitted onto the workpiece is erroneously emitted from the laser machining apparatus to the human body or peripheral devices, there is a possibility of the human body, etc. being damaged. In a portal laser machining apparatus having a laser nozzle attached vertically downward and movable in the horizontal and vertical directions, a laser beam is emitted downward in the vertical direction from the laser nozzle, and hence, the laser beam is normally prevented from being erroneously emitted to the distance. Thus, according to the portal laser machining apparatus, normally, the danger due to the mis-emission of the laser beam does not occur. On the other hand, in the laser robot where a laser nozzle mounted to a distal end of a robot arm is permitted to assume various positions and orientations, the laser beam can be erroneously emitted to the distance. This is dangerous.